1. Field of the Invention
The present invention relates to a plating pretreatment apparatus and a plating treatment method for a multi-cylinder block, and particularly, to a plating pretreatment apparatus and method that can individually control flow rate of a treatment liquid supplied to and the current and voltage applied to each of a plurality of cylinders of a multi-cylinder block.
2. Description of the Related Art
There are methods and apparatuses that perform a plating pretreatment of a cylinder inner wall surface of each of a plurality of cylinders of a multi-cylinder block. The plating pretreatment involves a chemical reaction, and therefore, temperature control is highly important to uniformly achieve the plating pretreatment.
For example, the plating pretreatment method and apparatus described in Patent Document 1 (Japanese Patent Laid-Open No. 9-3687) use a heater inserted in each cylinder and perform a plating pretreatment of the cylinder inner wall surface of each cylinder while heating the treatment liquid in the cylinder by controlling the temperature of the heater.
However, in the case where the plating pretreatment includes an electrochemical etching treatment that involves circulation of the treatment liquid, there causes an inconvenience that an electrode and a piping jig are placed in the cylinder, so that the cylinder cannot accommodate the heater, and therefore, the temperature control is impracticable.
In addition, according to Patent Document 1, four cylinders contain heaters, respectively, and the four heaters are controlled by a single temperature controller. Thus, the temperature of the heater may vary among the cylinders, and as a result, the plating pretreatment may be non-uniform among the cylinders.
Furthermore, according to Patent Document 1, what is controlled is not the temperature of the treatment liquid but the temperature of the heaters. Therefore, in the case where the cylinders are cold and draw much heat from the treatment liquid, a significant temperature difference may occur between the heaters and the treatment liquid, resulting in inappropriate heating of the treatment liquid even if the temperature of the heaters is controlled.